What is War?

By Kyle Jackson '27

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For the United States to be formally at war, Congress must issue a declaration by a majority vote in both houses, as stated by Article 1, Section 8 of the US Constitution. (1) Yet the United States has engaged in multiple large-scale conflicts, such as Korea, Vietnam, the Gulf War, Iraq, and Afghanistan, without ever making that declaration.

The United States has not been formally at war since World War II, even though large-scale conflicts have been plentiful in the eighty years since. Politically, they are called war, but formally, they are not. Historically, a formal declaration of war has a few critical components. Article 1, Section 8, Clause 11 of the Constitution says that Congress has the power “To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water.” (2) All 11 declarations of war in the history of the United States have started with the president requesting a declaration of war from Congress, citing a clear threat. All that is required is a simple majority by both chambers of Congress, then the President signs that joint resolution declaring a “state of war.” (3) The dictionary defines war as “a state of usually open and declared armed hostile conflict between states or nations. (4) The once very clear distinction between declared war and armed conflict has been deliberately and systematically eroded through the escalation of armed conflicts evolving into wars over the past eighty years.

Past Precedents with Conflicts Historically Considered Wars

The Constitution grants Congress the power to declare war, but alternative mechanisms have allowed presidents to obtain wartime authority without that formal step. In practice, war has come to be defined by scale and length, even if Congress doesn’t formally declare it. There are ways to circumvent that formal declaration, such as a resolution, which is what happened during the Vietnam War. In 1964, after US naval vessels were bombarded twice in North Vietnamese waters, the President asked Congress for the authority to escalate military involvement. Congress passed a joint resolution titled the Gulf of Tonkin Resolution. This resolution gave President Johnson the authority to increase US military involvement in the conflict between North and South Vietnam. (5) At this starting point, Johnson had the backing of the government to escalate in Vietnam. The result was a conflict that, in every practical sense, was a war, without ever being declared as one.

Korea followed a similar pattern, predating the war in Vietnam. In the aftermath of World War II, the big question was how to curb Soviet and more broadly communist expansion. A spirited debate took place between Congress and Truman over congressional authorization for 100,000 troops to deploy to Korea. The Senate argued that the President needed congressional approval, and the administration took the position that his Constitutional power as commander-in-chief allowed him to send troops anywhere in the world. An agreement was reached permitting Truman to send no more than four divisions on his own executive authority. When questioned by members of Congress as the conflict began to escalate to that textbook definition of war, the administration argued that it was “international police action”. (6) The precedent was set: armed conflict and declared war were no longer the same.

A further blurring mechanism is the Authorization for Use of Military Force (AUMF). (7) It acts as a loophole for a much more well-known resolution called the War Powers Resolution of 1973. The War Powers Act, enforced after the Vietnam War, is meant to check executive military power to stop prolonged, open-ended conflicts. Under this specific resolution, the President can only commit hostilities in three scenarios: a declaration of war, an AUMF, or a direct attack on the United States. Once hostilities begin, the Speaker of the House and President Pro Tempore of the Senate must be informed within 48 hours of engagement. After that, the Executive Branch has sixty calendar days to obtain congressional authorization or withdraw forces. (8)

An AUMF, once passed by Congress, eliminates the time limit, granting the President the power to take whatever action deemed necessary to satisfy their objective. The most significant modern example came after the September 11, 2001 terrorist attacks. Under the authority granted by the AUMF of 2001, military operations began in Afghanistan. However, the United States did not stop in Afghanistan, they expanded throughout the Middle East, from Yemen, Syria, Somalia, and Pakistan. (9) As a result, that resolution justified the military’s presence in that particular area in the Middle East for over twenty years, without a formal declaration of war.

The war in Afghanistan is often referred to as one of America’s longest wars, even though the war was never declared. That war ended with President Biden issuing an order to withdraw from Afghanistan. (10) The AUMF was never repealed, which means it could be put into effect in the present day. Further emphasizing the line between smaller armed conflicts and full-scale war has been eroding for decades.

The Present

The United States finds itself in a familiar predicament. Being engaged in armed conflict overseas, long enough that it would fit that textbook definition of war, though no war has been declared. At the end of February 2026, the United States, in coordination with Israel, conducted a series of airstrikes resulting in the death of Iran's Supreme Leader, the Ayatollah. What makes the current situation distinct is that there have been no constitutional or legal sidesteps to counter the barrier of a formal war declaration.

On paper, there is nothing officially keeping it in the armed conflict territory. It is important to note that the sixty-day limit has not been met yet. President Trump has justified military action through the “Commander in Chief Clause”. This clause states, “The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States." (11) The administration’s continued justification of the war was that the preemptive strike was to defend against anticipated attacks. This line of reasoning is covered by the Executive Branch’s Article 2 power, which has been used to explain the first Trump administration’s threat to North Korea in 2018. (12)

Beyond that, no new AUMFs have been filed, and only twenty days are left before further action must be taken by the legislative branch. With Iran’s head of state deceased, and strikes ongoing, this conflict emphasizes the almost non-existent line between armed conflicts and formal war declaration.

The one legal tool that could redraw the line is the War Powers Resolution. The War Powers Resolution being floated in Congress right now is the only instrument that could redraw that vastly eroded line. Separate from the War Powers Act of 1973, this would limit what the President can do beyond congressional approval for this particular situation. The likelihood of this passing remains slim, as of April 15, 2026, the fourth war powers resolution has failed with a 52-47 vote. The Democratic minority has pledged to vote on a similar measure every week, creating a public record of where each senator stands. (13) For all intents and purposes, the United States is at war.

The Line in the Sand

Armed conflict and declared war by definition are not the same. Under Article 1, Section 8 of the United States Constitution, war can only be declared formally through an act of Congress, a process that has not been used since World War II. Yet by textbook definition, the United States has been entangled in multiple wars since then. Through resolutions, AUMFs, and executive authority, war can be waged without declaration. Emphasized by modern history through numerous conflicts that match the war definition. Slowly eroding the line between smaller contained armed conflicts and active wars. In the present day, that line is virtually nonexistent, illustrated through the war in Iran, where scale and length match the practical definition of war. Setting a new precedent of being at war in everything, but the constitutional definition.

Endnotes

1. "Article I, Section 8, Clause 11: Overview of the Declare War Clause," Constitution Annotated, accessed April 16, 2026, https://constitution.congress.gov/browse/essay/artI-S8-C11-2-1/ALDE_00000110/.

2. Ibid.

3. "How Does the US Officially Declare War?" History.com, March 4, 2026, https://www.history.com/articles/us-officially-declare-war-constitution-congress.

4. "War," Merriam-Webster, accessed April 15, 2026, https://www.merriam-webster.com/dictionary/war.

5. "Tonkin Gulf Resolution (1964)," National Archives and Records Administration, accessed April 15, 2026, https://www.archives.gov/milestone-documents/tonkin-gulf-resolution.

6. "The Declare War Clause, Part 7: The Cold War and Korean War," Congress.gov, accessed April 16, 2026, https://www.congress.gov/crs-product/LSB11236.

7. LegalClarity Team, "What Is an AUMF? Congress, Courts, and War Powers," LegalClarity, April 1, 2026, https://legalclarity.org/what-is-an-aumf-authorization-for-use-of-military-force/.

8. "2001 Authorization for Use of Military Force: Issues Concerning Its Continued Application," Congress.gov, accessed April 16, 2026, https://www.congress.gov/crs-product/R43983.

9. Ibid.

10. Terri Moon Cronk, "Biden Announces Full US Troop Withdrawal from Afghanistan by Sept. 11," U.S. Department of Defense, April 14, 2021, https://www.defense.gov/News/News-Stories/Article/article/2573268/biden-announces-full-us-troop-withdrawal-from-afghanistan-by-sept-11/.

11. "Commander in Chief Powers," Legal Information Institute, accessed April 15, 2026, https://www.law.cornell.edu/wex/commander_in_chief_powers.

12. "Does Trump Have the Authority to Strike Iran?" Council on Foreign Relations, accessed April 15, 2026, https://www.cfr.org/articles/does-trump-have-authority-strike-iran.

13. Ana Faguy, "Vote to Stop Iran War Fails in US Senate Again but Democrats Vow to Keep Trying," BBC News, April 15, 2026, https://www.bbc.com/news/articles/czxrrlve714o.